Mining, Metallurgy & Exploration

, Volume 36, Issue 3, pp 513–521 | Cite as

Evaluation of Post-blast Re-entry Times Based on Gas Monitoring of Return Air

  • D. BahramiEmail author
  • L. Yuan
  • J. H. Rowland
  • L. Zhou
  • R. Thomas


Blasting is the main method of production in many non-coal underground mining operations and produces multiple toxic gases as a result. The Mine Safety and Health Administration (MSHA) requires mine operators to measure the level of toxic gases in mines as frequently as necessary to ensure they are below regulatory safety limits. The current practice uses portable gas monitors to check the concentrations of toxic gases after a fixed post-blast time. This paper studies the application of a gas monitoring system in the return entry of a limestone mine to determine a safe re-entry time. The National Institute for Occupational Safety and Health (NIOSH) conducted such a monitoring program in a limestone mine from September 2016 through May 2018. NIOSH/PMRD (Pittsburgh Mining Research Division) is endeavoring to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions. This study showed that the use of gas monitoring in the return air can be a useful tool at the mine operator’s disposal to detect and reduce the risk of hazardous conditions and also to reliably estimate the re-entry time.


Ventilation Blasting Re-entry time Gas monitoring Contaminant spread 



The authors wish to thank John Soles of the Pittsburgh Mining Research Division for conducting measurements during this study.

Compliance with Ethical Standards


The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention.

Conflict of Interest

The authors declare that they have no conflict of interest.


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Copyright information

© This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection 2019

Authors and Affiliations

  1. 1.CDC NIOSHPittsburghUSA

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